ZDEF and sigma/pressure vertical coordinates

[Tero Siili]

Dear fellow GrADSers,

we have GRIB data (32 vertical levels, level 1 at the top, 32 nearest
to the surface). The model producing these data is developed from the
HIRLAM. So far we gave used in our control files for ZDEF

ZDEF 0 LINEAR 1 1

which gives the vertical axis with level numbers.

What I would like to accomplish is to use the sigma levels by
specifying them in the ZDEF. To me the obvious modification is

ZDEF 32 LEVELS 0.009375 0.01875 0.0375 0.075 0.125 0.175 0.225 0.275
0.325 0.375 0.425 0.475 0.525 0.575 0.625 0.675 0.725 0.775 0.825
0.875 0.91 0.93 0.9475 0.96 0.97 0.9775 0.9825 0.9875 0.9925 0.997
0.99935 0.99985

I have

1) run the control file through gribmap
2) started gradsc
3) opened the control file
4) fixed lat, lon, t to supposedly valid region
5) set lev 1 32

To my understanding this should produce a profile with the sigma
values as the vertical axis, but the response is data undefined. I
have tried with and without OPTIONS ZREV, to no avail. The original
ZDEF approach does produce at least something.

What am I doing wrong --- or is this just something GrADS is unable
to do?


Tero Siili
SOHO Science Operations Coordinator